1. Field of the Invention
The invention relates to a method and apparatus for machining workpieces, and more particularly to a machine tool equipped in a novel way with a tool turret to enable machining of wavy or tubular workpieces.
2. Prior Art
EP 0 978 351 A2 describes a device for machining workpieces with at least two adjacently arranged lathes that respectively contain a vertically arranged, rotationally driven work spindle for clamping the workpiece and at least one device for accommodating several machining tools. The rotational axes of all lathes are essentially arranged vertically in this case, and one rotating/pivoting device is respectively provided between the lathes in order to transfer the workpiece from one lathe to the next lathe after each respective machining step is completed. One disadvantage of this arrangement can be seen in the fact that a completely separate lathe with its own control, its own drive, and its own miscellaneous equipment must be provided for each machining step that is to be carried out. Another disadvantage is that a separate rotating/pivoting device needs to be provided for each transfer from one lathe to the next lathe, significantly increases construction expenses.
DE 199 59 961 A1 describes a machine tool, in particular a lathe, with several vertical workpiece spindles, wherein the workpiece can be directly transferred from one spindle to another spindle by means of receiving devices for the workpiece provided on the respective spindles. This device can only be used for machining of very specific workpieces and is particularly unsuitable for any machining of wavy or tubular workpieces.
DE 199 50 706 C2 describes a device for clamping and/or holding workpieces on a machine tool. This device comprises a gripping element that is suitable for wavy or tubular workpieces and that can be arranged on the tool table of a machine tool. The gripping element requires its own holding arrangement and its own drive, and frequently obstructs the work region of a machine tool due to the small available space. In addition, its manufacture is comparatively expensive because the gripping element requires its own holding arrangement and its own drive.
German Utility Model DE 93 21 397 U1 pertains to a lathe, wherein a tool carrier may be equipped with a gripping hand that is able to take hold of the workpiece being machined in the associated spindle and deposit said workpiece from the top onto a delivery stack arranged adjacent to the lathe.
WO 01/89761 A1 describes a device for taking hold of and transporting workpieces in lathes with several machining stations, wherein two gripping devices arranged to the right and left of each machining station serve to take hold of, transport and position the workpieces. This device also has a tool turret. However, the device merely comprises a series of individual elements, in particular gripping elements and a tool turret, but no combination of these elements, so that significant construction expenses and correspondingly high costs result.